NAME

tcclasses - Shorewall6 file to define HTB classes

SYNOPSIS

/etc/shorewall6/tcclasses

DESCRIPTION

A note on the rate/bandwidth definitions used in this file:
· don't use a space between the integer value and the unit: 30kbit is
valid while 30 kbit is NOT.
· you can use one of the following units:
kpbs
Kilobytes per second.
mbps
Megabytes per second.
kbit
Kilobits per second.
mbit
Megabits per second.
bps or number
Bytes per second.
· if you want the values to be calculated for you depending on the
output bandwidth setting defined for an interface in tcdevices, you
can use expressions like the following:
full/3
causes the bandwidth to be calculated as 1/3 of the full
outgoing speed that is defined.
full*9/10
will set this bandwidth to 9/10 of the full bandwidth
Note that in a sub-class (a class that has a specified parent
class), full refers to the RATE or CEIL of the parent class rather
than to the OUT-BANDWIDTH of the device.
DO NOT add a unit to the rate if it is calculated !
The columns in the file are as follows.
INTERFACE - interface[:class]
Name of interface. Each interface may be listed only once in this
file. You may NOT specify the name of an alias (e.g., eth0:0) here;
see http://www.shorewall.net/FAQ.htm#faq18
You may specify either the interface number or the interface name.
If the classify option is given for the interface in
shorewall6-tcdevices[1](5), then you must also specify an interface
class (an integer that must be unique within classes associated
with this interface).
You may NOT specify wildcards here, e.g. if you have multiple ppp
interfaces, you need to put them all in here!
Please note that you can only use interface names in here that have
a bandwidth defined in the shorewall6-tcdevices[1](5) file.
Normally, all classes defined here are sub-classes of a root class
that is implicitly defined from the entry in
shorewall6-tcdevices[1](5). You can establish a class hierarchy by
specifying a parent class -- the number of a class that you have
previously defined. The sub-class may borrow unused bandwidth from
its parent.
MARK - {-|value}
The mark value which is an integer in the range 1-255. You set mark
values in the shorewall6-tcrules[2](5) file, marking the traffic
you want to fit in the classes defined in here. Must be specified
as '-' if the classify option is given for the interface in
shorewall6-tcdevices[1](5)
You can use the same marks for different interfaces.
RATE - rate[:dmax[:umax]]
The minimum bandwidth this class should get, when the traffic load
rises. If the sum of the rates in this column exceeds the
INTERFACE's OUT-BANDWIDTH, then the OUT-BANDWIDTH limit may not be
honored. Similarly, if the sum of the rates of sub-classes of a
class exceed the CEIL of the parent class, things don't work well.
When using the HFSC queuing discipline, leaf classes may specify
dmax, the maximum delay in milliseconds that the first queued
packet for this class should experience. May be expressed as an
integer, optionally followed by 'ms' with no intervening white
space (e.g., 10ms).
HFSC leaf classes may also specify umax, the largest packet
expected in this class. May be expressed as an integer. The unit of
measure is bytes and the integer may be optionally followed by 'b'
with no intervening white space (e.g., 800b). umax may only be
given if dmax is also given.
CEIL - rate
The maximum bandwidth this class is allowed to use when the link is
idle. Useful if you have traffic which can get full speed when more
needed services (e.g. ssh) are not used.
You can use the value full in here for setting the maximum
bandwidth to the RATE of the parent class, or the OUT-BANDWIDTH of
the device if there is no parent class.
PRIORITY - priority
The priority in which classes will be serviced by the packet
shaping scheduler and also the priority in which bandwidth in
excess of the rate will be given to each class.
Higher priority classes will experience less delay since they are
serviced first. Priority values are serviced in ascending order
(e.g. 0 is higher priority than 1).
Classes may be set to the same priority, in which case they will be
serviced as equals.
OPTIONS (Optional) - [option[,option]...]
A comma-separated list of options including the following:
default
This is the default class for that interface where all traffic
should go, that is not classified otherwise.
Note
You must define default for exactly one class per
interface.
tos=0xvalue[/0xmask] (mask defaults to 0xff)
This lets you define a classifier for the given value/mask
combination of the IP packet's TOS/Precedence/DiffSrv octet
(aka the TOS byte).
tos-tosname
Aliases for the following TOS octet value and mask encodings.
TOS encodings of the "TOS byte" have been deprecated in favor
of diffserve classes, but programs like ssh, rlogin, and ftp
still use them.
tos-minimize-delay 0x10/0x10
tos-maximize-throughput 0x08/0x08
tos-maximize-reliability 0x04/0x04
tos-minimize-cost 0x02/0x02
tos-normal-service 0x00/0x1e
Note
Each of these options is only valid for ONE class per
interface.
tcp-ack
If defined, causes a tc filter to be created that puts all tcp
ack packets on that interface that have a size of <=64 Bytes to
go in this class. This is useful for speeding up downloads.
Please note that the size of the ack packets is limited to 64
bytes because we want only packets WITHOUT payload to match.
Note
This option is only valid for ONE class per interface.
flow=keys
Shorewall attaches an SFQ queuing discipline to each leaf HTB
class. SFQ ensures that each flow gets equal access to the
interface. The default definition of a flow corresponds roughly
to a Netfilter connection. So if one internal system is running
BitTorrent, for example, it can have lots of 'flows' and can
thus take up a larger share of the bandwidth than a system
having only a single active connection. The flow classifier
(module cls_flow) works around this by letting you define what
a 'flow' is. The clasifier must be used carefully or it can
block off all traffic on an interface! The flow option can be
specified for an HTB leaf class (one that has no sub-classes).
We recommend that you use the following:
Shaping internet-bound traffic:
flow=nfct-src
Shaping traffic bound for your local net:
flow=dst
These will cause a 'flow' to consists of the traffic to/from
each internal system.
When more than one key is give, they must be enclosed in
parenthesis and separated by commas.
To see a list of the possible flow keys, run this command: tcfilteraddflowhelp Those that begin with "nfct-" are
Netfilter connection tracking fields. As shown above, we
recommend flow=nfct-src; that means that we want to use the
source IP address beforeNAT as the key.
pfifo
When specified for a leaf class, the pfifo queing discipline is
applied to the class rather than the sfq queuing discipline.
limit=number
Added in Shorewall 4.4.3. When specified for a leaf class,
determines the maximum number of packets that may be queued
within the class. The number must be > 2 and <= 128. If not
specified, the value 127 is assumed.

EXAMPLES

Example 1:
Suppose you are using PPP over Ethernet (DSL) and ppp0 is the
interface for this. You have 4 classes here, the first you can use
for voice over IP traffic, the second interactive traffic (e.g.
ssh/telnet but not scp), the third will be for all unclassified
traffic, and the forth is for low priority traffic (e.g.
peer-to-peer).
The voice traffic in the first class will be guaranteed a minimum
of 100kbps and always be serviced first (because of the low
priority number, giving less delay) and will be granted excess
bandwidth (up to 180kbps, the class ceiling) first, before any
other traffic. A single VOIP stream, depending upon codecs, after
encapsulation, can take up to 80kbps on a PPOE/DSL link, so we pad
a little bit just in case. (TOS byte values 0xb8 and 0x68 are
DiffServ classes EF and AFF3-1 respectively and are often used by
VOIP devices).
Interactive traffic (tos-minimum-delay) and TCP acks (and ICMP echo
traffic if you use the example in tcrules) and any packet with a
mark of 2 will be guaranteed 1/4 of the link bandwidth, and may
extend up to full speed of the link.
Unclassified traffic and packets marked as 3 will be guaranteed
1/4th of the link bandwidth, and may extend to the full speed of
the link.
Packets marked with 4 will be treated as low priority packets. (The
tcrules example marks p2p traffic as such.) If the link is
congested, they're only guaranteed 1/8th of the speed, and even if
the link is empty, can only expand to 80% of link bandwidth just as
a precaution in case there are upstream queues we didn't account
for. This is the last class to get additional bandwidth and the
last to get serviced by the scheduler because of the low priority.
#INTERFACE MARK RATE CEIL PRIORITY OPTIONS
ppp0 1 100kbit 180kbit 1 tos=0x68/0xfc,tos=0xb8/0xfc
ppp0 2 full/4 full 2 tcp-ack,tos-minimize-delay
ppp0 3 full/4 full 3 default
ppp0 4 full/8 full*8/10 4